Patent GB-624554-A (GB)
Title: Improvements in or relating to apparatus for controlling a dirigible craft from a bomb-sight
IPC: B64D1/06
Filed: 1942-07-01
Abstract: 624,554. Bomb sights. SPERRY GYROSCOPE CO., Inc. July 1, 1942, No. 9128. Convention date, April 9, 1941. [Class 92 (ii)] [Also in Group XXXIII] Apparatus for controlling a dirigible craft from a bomb sight 5, Fig. 1B, comprises means for turning the sight in azimuth and for simultaneously determining a proportional turn to be imparted to the craft, means also being provided for varying the ratio of the turn of the sight to that of the craft. Stabilizing in azimuth of the sight shown is effected by a gyroscope 4, Fig. 2, having an inductive pick-off 89 adapted to drive a reversible motor 92. The latter drives a shaft 95 which is geared to a follow-up device 88 on the gyroscope and which drives, through a clutch 96, Fig. 1C, and differential 97, the shafts 98 and 100 leading to the base of the sighting device. The mechanism for rotating the sight and aircraft in azimuth comprises a disc 105, Fig. 1C, driven by a motor 25 and serving to drive a shaft 116 through adjustable ball-carriage mechanism 108 and a change-speed gear 117, 118. When it is desired to displace the sight quickly to find the target a knob 114 connected by shafts 1031, 98 and 100 to the base of the sight is rotated. After the target is sighted and it is desired to bring the aircraft on the straight ground track towards the target, a knob 109 is turned. The turning of the knob moves the ball carriage 108 and thereby affects the speed of rotation of the shafts leading to the sighting device. At the same time a member 120 is lifted out of a notch in a disc 121 and thereby moves a switch of a relay controlling the gear 117, 118 and causes rapid rotation of the shaft 116 which leads to the mechanism controlling the aircraft. As shown in Fig. 2, the shaft 116 is geared to the armature of a selsyn transmitter 134, the field of which is geared to shaft 95 of the follow-up device 88. When a switch 131 is in one position the transmitter is connected to a selsyn signal generator in an amplifier 133 and the latter is adapted to actuate a servo device 132 associated with the rudder 142. In the other position of the switch the transmitter is connected to a selsyn repeater motor 138 and an indicator 139 informs the pilot of the correct course to take. A different ratio between the movements of the craft and sight may be obtained by moving the member 118 of the shaft 116 to its other position. The sighting device comprises a telescopic sight 5, reticule 1, mirror 6, and prisms 7, 8 and 9. The prisms 7 and 9 are adjustable about vertical and horizontal axes respectively, and means are provided in conjunction with prism 9 to maintain the line of sight continuously on the target. Such means consist of the electric motor 25 which drives a disc 24 through gearing 26, cylinder 23 and ball carriage 22. The speed of rotation of the disc is varied by adjusting the radial position of the ball carriage, adjustment being effected by a screw 104 on shaft 21. Rotation of this shaft also rotates fine and coarse dials 29, 29<SP>1</SP> and 30, 301 which indicate the time of fall of the bomb as known from the altitude. The pairs 29, 30 and 29<SP>1</SP>, 30<SP>1</SP> are read for high and low altitudes respectively, and a change-speed gear device 27 is provided in the gearing from motor 25 to disc 24 for operation when a change over from reading one pair of dials to the other is necessitated. A radially adjustable ball carriage is also provided on the other face of the disc and drives a shaft 50, the latter being connected by gearing 51, 52, 53 to a shaft 54, geared to a cam 13, which is adapted to tilt the prism 9 through a bell-crank 12. The angular speed of the shaft 50, and hence of the prism, is varied when desired by a knob 46 on shaft 47, the latter being geared to a shaft 45 having a screw connection with the ball carriage 43. A quick positioning of the prism may be effected by a knob 56. In operation, the sight is manually directed on the target by knob 56 and automatically held on the target by the rotation of prism 9 through the drive from disc 21, the bombs being released at the correct moment by the closing of contacts 68, 76, of which the contact 76 is connected, as shown in Figure 1B, to the shaft 79 of the cam 13. The contact 68 is mounted for axial movement on the screw-threaded portion of a shaft 67 which is geared to a shaft 64, geared in turn to the shaft carrying the knob 146. Contact 68 is also moved towards or away from contact 76, to allow for trail correction, by mechanism comprising a circular rack 75 and pinion 74, the latter being geared to a shaft carrying a knob 70 and scale 71. An alternative pair of contacts 76<SP>1</SP>, 168, similarly actuated is provided for high altitude bombing. The turning of the knob 70 also longitudinally positions a cam pin 80 on a solid cam 81, driven by the shaft 79 of cam 13, the pin 80 being connected by shafts and levers to the prism 7 to position the latter in order to introduce the correct cross trail angle. A further knob 143 suitably geared to a drift angle indicator 144 is provided to give the necessary corrections when a side wind is present. The knob is mounted on a shaft which is geared to the shaft 100 for moving the sight in azimuth and to a rack-and-pinion device 147 serving to move the pin 148 on which lever 149, leading to prism 7, pivots. Specification 624,555 is referred to.